The Alabama bill, passed by the state Legislature late Tuesday, includes a requirement that an abortion provider have admitting rights at a local hospital – a rule that may sound minor, but could prove challenging to achieve in a state with strong opposition to abortion. Supporters say it is aimed at protecting women’s health, while opponents say it is medically unnecessary and aimed at denying women access to abortion.

Last week, North Dakota became the most restrictive state in the country toward abortion when the governor signed a bill banning abortion as soon as a fetal heartbeat is detected – as early as six weeks. North Dakota also requires abortion doctors to have admitting privileges, as do Mississippi and Tennessee. Early in March, Arkansas passed a fetal-heartbeat law that would ban abortion as early as 12 weeks.

Also taking action on abortion, but along a different track, is Virginia. On Tuesday, the legislature approved a measure proposed by Gov. Robert McDonnell (R) that would forbid insurers in federally managed "exchanges" from covering abortion under the Affordable Care Act (ACA).

The immediate answer is that, following the November elections, states across the country have just seated their new legislatures – and for some members, taking action against abortion rights is a top priority. In Virginia, Governor McDonnell is moving fast on abortion as the clock winds down toward the Oct. 1 start of open enrollment for health insurance under the ACA.

A wave of state-level activism against abortion rights has been under way for the past 12 years, but it picked up steam in 2011, following the birth of the conservative tea party movement. In the 2010 elections, tea partyers won big in some state legislatures. Though their main focus is fiscal issues, most are also social conservatives – many of them driven to enact abortion restrictions soon after taking office.

In 2011, 92 abortion restrictions were enacted in state legislatures, and in 2012, the number was 43, according to Elizabeth Nash of the Guttmacher Institute, a research organization on reproductive issues.

“Those are the two highest years,” says Ms. Nash. “We’re in the midst of this wave of abortion restrictions.”

For the larger context, she says, go back to the start of the last decade. In 2000, Guttmacher classified 13 states as being “hostile” to abortion. By 2011, half the states were hostile. To gauge “hostility,” Guttmacher identified 10 classifications of abortion restriction, and if a state reached four of them, it was called hostile.

Many of the restrictions have been or will be legally enjoined from taking effect, amid challenges to their constitutionality. Some could wind up in the Supreme Court, presenting an opportunity for the justices to take another look at Roe v. Wade, the landmark ruling in 1973 that legalized abortion nationwide.

Within the antiabortion movement, there’s a longstanding debate over how best to proceed on the legal front: Go for measures that openly flout Roe – such as fetal heartbeat legislation or so-called “personhood” amendments to state constitutions – or try to chip away at abortion rights through seemingly less restrictive measures.

Alabama seems aimed down the latter path. Gov. Robert Bentley (R) of Alabama is expected to sign the bill requiring hospital admitting privileges for abortion providers. Mississippi passed a similar requirement last year, but a federal judge blocked it from taking effect while litigation is under way.

Americans United for Life (AUL), which provides model legislation to state legislators wishing to enact restrictions on abortion, applauded Alabama’s move.

“To keep women and girls safe, abortion clinics nationwide should be held to the same high standards that we expect from any outpatient medical facility,” said Charmaine Yoest, president and CEO of AUL, in a statement. “Alabama is leading the way with the passage of the Women’s Health and Safety Act.”